<?php
/**
 * CodeIgniter
 *
 * An open source application development framework for PHP
 *
 * This content is released under the MIT License (MIT)
 *
 * Copyright (c) 2014 - 2015, British Columbia Institute of Technology
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 * @package    CodeIgniter
 * @author    EllisLab Dev Team
 * @copyright    Copyright (c) 2008 - 2014, EllisLab, Inc. (http://ellislab.com/)
 * @copyright    Copyright (c) 2014 - 2015, British Columbia Institute of Technology (http://bcit.ca/)
 * @license    http://opensource.org/licenses/MIT    MIT License
 * @link    http://codeigniter.com
 * @since    Version 1.3.0
 * @filesource
 */
defined('BASEPATH') OR exit('No direct script access allowed');

/**
 * ODBC Database Adapter Class
 *
 * Note: _DB is an extender class that the app controller
 * creates dynamically based on whether the query builder
 * class is being used or not.
 *
 * @package        CodeIgniter
 * @subpackage    Drivers
 * @category    Database
 * @author        EllisLab Dev Team
 * @link        http://codeigniter.com/user_guide/database/
 */
class CI_DB_odbc_driver extends CI_DB {

    /**
     * Database driver
     *
     * @var    string
     */
    public $dbdriver = 'odbc';

    /**
     * Database schema
     *
     * @var    string
     */
    public $schema = 'public';

    // --------------------------------------------------------------------

    /**
     * Identifier escape character
     *
     * Must be empty for ODBC.
     *
     * @var    string
     */
    protected $_escape_char = '';

    /**
     * ESCAPE statement string
     *
     * @var    string
     */
    protected $_like_escape_str = " {escape '%s'} ";

    /**
     * ORDER BY random keyword
     *
     * @var    array
     */
    protected $_random_keyword = array('RND()', 'RND(%d)');

    // --------------------------------------------------------------------

    /**
     * Class constructor
     *
     * @param    array    $params
     * @return    void
     */
    public function __construct($params)
    {
        parent::__construct($params);

        // Legacy support for DSN in the hostname field
        if (empty($this->dsn))
        {
            $this->dsn = $this->hostname;
        }
    }

    // --------------------------------------------------------------------

    /**
     * Non-persistent database connection
     *
     * @param    bool    $persistent
     * @return    resource
     */
    public function db_connect($persistent = FALSE)
    {
        return ($persistent === TRUE)
            ? odbc_pconnect($this->dsn, $this->username, $this->password)
            : odbc_connect($this->dsn, $this->username, $this->password);
    }

    // --------------------------------------------------------------------

    /**
     * Execute the query
     *
     * @param    string    $sql    an SQL query
     * @return    resource
     */
    protected function _execute($sql)
    {
        return odbc_exec($this->conn_id, $sql);
    }

    // --------------------------------------------------------------------

    /**
     * Begin Transaction
     *
     * @param    bool    $test_mode
     * @return    bool
     */
    public function trans_begin($test_mode = FALSE)
    {
        // When transactions are nested we only begin/commit/rollback the outermost ones
        if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
        {
            return TRUE;
        }

        // Reset the transaction failure flag.
        // If the $test_mode flag is set to TRUE transactions will be rolled back
        // even if the queries produce a successful result.
        $this->_trans_failure = ($test_mode === TRUE);

        return odbc_autocommit($this->conn_id, FALSE);
    }

    // --------------------------------------------------------------------

    /**
     * Commit Transaction
     *
     * @return    bool
     */
    public function trans_commit()
    {
        // When transactions are nested we only begin/commit/rollback the outermost ones
        if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
        {
            return TRUE;
        }

        $ret = odbc_commit($this->conn_id);
        odbc_autocommit($this->conn_id, TRUE);
        return $ret;
    }

    // --------------------------------------------------------------------

    /**
     * Rollback Transaction
     *
     * @return    bool
     */
    public function trans_rollback()
    {
        // When transactions are nested we only begin/commit/rollback the outermost ones
        if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
        {
            return TRUE;
        }

        $ret = odbc_rollback($this->conn_id);
        odbc_autocommit($this->conn_id, TRUE);
        return $ret;
    }

    // --------------------------------------------------------------------

    /**
     * Platform-dependant string escape
     *
     * @param    string
     * @return    string
     */
    protected function _escape_str($str)
    {
        return remove_invisible_characters($str);
    }

    // --------------------------------------------------------------------

    /**
     * Affected Rows
     *
     * @return    int
     */
    public function affected_rows()
    {
        return odbc_num_rows($this->result_id);
    }

    // --------------------------------------------------------------------

    /**
     * Insert ID
     *
     * @return    bool
     */
    public function insert_id()
    {
        return ($this->db->db_debug) ? $this->db->display_error('db_unsupported_feature') : FALSE;
    }

    // --------------------------------------------------------------------

    /**
     * Show table query
     *
     * Generates a platform-specific query string so that the table names can be fetched
     *
     * @param    bool    $prefix_limit
     * @return    string
     */
    protected function _list_tables($prefix_limit = FALSE)
    {
        $sql = "SELECT table_name FROM information_schema.tables WHERE table_schema = '".$this->schema."'";

        if ($prefix_limit !== FALSE && $this->dbprefix !== '')
        {
            return $sql." AND table_name LIKE '".$this->escape_like_str($this->dbprefix)."%' "
                .sprintf($this->_like_escape_str, $this->_like_escape_chr);
        }

        return $sql;
    }

    // --------------------------------------------------------------------

    /**
     * Show column query
     *
     * Generates a platform-specific query string so that the column names can be fetched
     *
     * @param    string    $table
     * @return    string
     */
    protected function _list_columns($table = '')
    {
        return 'SHOW COLUMNS FROM '.$table;
    }

    // --------------------------------------------------------------------

    /**
     * Field data query
     *
     * Generates a platform-specific query so that the column data can be retrieved
     *
     * @param    string    $table
     * @return    string
     */
    protected function _field_data($table)
    {
        return 'SELECT TOP 1 FROM '.$table;
    }

    // --------------------------------------------------------------------

    /**
     * Error
     *
     * Returns an array containing code and message of the last
     * database error that has occured.
     *
     * @return    array
     */
    public function error()
    {
        return array('code' => odbc_error($this->conn_id), 'message' => odbc_errormsg($this->conn_id));
    }

    // --------------------------------------------------------------------

    /**
     * Update statement
     *
     * Generates a platform-specific update string from the supplied data
     *
     * @param    string    $table
     * @param    array    $values
     * @return    string
     */
    protected function _update($table, $values)
    {
        $this->qb_limit = FALSE;
        $this->qb_orderby = array();
        return parent::_update($table, $values);
    }

    // --------------------------------------------------------------------

    /**
     * Truncate statement
     *
     * Generates a platform-specific truncate string from the supplied data
     *
     * If the database does not support the TRUNCATE statement,
     * then this method maps to 'DELETE FROM table'
     *
     * @param    string    $table
     * @return    string
     */
    protected function _truncate($table)
    {
        return 'DELETE FROM '.$table;
    }

    // --------------------------------------------------------------------

    /**
     * Delete statement
     *
     * Generates a platform-specific delete string from the supplied data
     *
     * @param    string    $table
     * @return    string
     */
    protected function _delete($table)
    {
        $this->qb_limit = FALSE;
        return parent::_delete($table);
    }

    // --------------------------------------------------------------------

    /**
     * Close DB Connection
     *
     * @return    void
     */
    protected function _close()
    {
        odbc_close($this->conn_id);
    }

}
